Have your child stand on the printed sheet and read their size directly. Covers toddler to youth: US 4T – 6Y (foot ~11.4 – 24.1 cm, roughly ages 1–12). Kids' sizing is unisex — one chart works for boys and girls. T = Toddler, Y = Youth.
Print settings (critical): scale 100% / “Actual size”, never “Fit to page”. Paper A4, portrait, margins “None”. Turn off browser header/footer. After printing, check the credit-card box (must fit a real card exactly: 85.60 × 53.98 mm) and the 10 cm bar with a ruler. If either is off, reprint — do not measure.
Press Print below (or Save as PDF, then print the PDF at 100%). Best in the afternoon, when feet are largest.
Put the sheet on a hard floor against a wall. Heel on the HEEL line, lightly touching the wall.
Child stands with full weight. Mark the longest toe, read the nearest size line. Measure both feet, use the larger.
Leave a thumb's width (~12 mm) of growing room in front of the longest toe when buying.